mitts 0.3.21

Rust-first build and package tooling with a shared artifact cache
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140

# Mitts Build — optional provenance inputs must not force every Cargo invocation.
# Copyright (c) 2026 Alexander Panasenko
# Contact: alex@prod.codes
# Author: https://prod.codes/about/
# Project: https://github.com/alex09x/mitts
# SPDX-License-Identifier: MIT OR Apache-2.0
import json
import os
import subprocess
import tempfile
import unittest
from pathlib import Path

ROOT = Path(__file__).resolve().parents[2]


class BuildMetadataTests(unittest.TestCase):
    def setUp(self):
        temporary = tempfile.TemporaryDirectory()
        self.addCleanup(temporary.cleanup)
        self.root = Path(temporary.name)
        self.project = self.root / "project"
        (self.project / "src").mkdir(parents=True)
        self.counter = self.root / "counter"
        (self.project / "Cargo.toml").write_text(
            '[package]\nname="metadata-fixture"\nversion="0.1.0"\nedition="2021"\n'
        )
        (self.project / "Cargo.lock").write_text(
            'version=4\n[[package]]\nname="metadata-fixture"\nversion="0.1.0"\n'
        )
        (self.project / "src/lib.rs").write_text(
            '#[test]\nfn provenance() { assert_eq!(env!("MITTS_GIT_SHA"), '
            'std::env::var("EXPECTED_SOURCE_SHA").unwrap()); }\n'
        )
        code = (ROOT / "build.rs").read_text()
        instrumentation = """
    let counter = std::env::var("BUILD_METADATA_COUNTER").unwrap();
    let count = std::fs::read_to_string(&counter).unwrap_or_default().parse::<u32>().unwrap_or(0);
    std::fs::write(&counter, (count + 1).to_string()).unwrap();
"""
        self.assertEqual(code.count("fn main() {"), 1)
        (self.project / "build.rs").write_text(
            code.replace("fn main() {", "fn main() {" + instrumentation)
        )
        self.env = {
            **os.environ,
            "BUILD_METADATA_COUNTER": str(self.counter),
            "CARGO_TARGET_DIR": str(self.root / "target"),
        }
        subprocess.run(
            ["cargo", "generate-lockfile", "--quiet"],
            cwd=self.project,
            env=self.env,
            check=True,
        )

    def git(self, *args):
        return subprocess.check_output(
            [
                "git",
                "-c",
                "user.name=Fixture",
                "-c",
                "user.email=fixture@example.com",
                "-c",
                "commit.gpgsign=false",
                *args,
            ],
            cwd=self.project,
            text=True,
        ).strip()

    def cargo(self, expected):
        result = subprocess.run(
            ["cargo", "test", "--quiet", "--lib"],
            cwd=self.project,
            env={**self.env, "EXPECTED_SOURCE_SHA": expected},
            text=True,
            capture_output=True,
            check=False,
        )
        self.assertEqual(result.returncode, 0, result.stdout + result.stderr)

    def test_git_checkout_caches_metadata_and_detects_new_commit(self):
        self.git("init", "-q")
        self.git("add", ".")
        self.git("commit", "-qm", "fixture")
        sha = self.git("rev-parse", "HEAD")
        self.cargo(sha)
        self.cargo(sha)
        self.assertEqual(self.counter.read_text(), "1")
        self.git("commit", "--allow-empty", "-qm", "next")
        self.cargo(self.git("rev-parse", "HEAD"))
        self.assertEqual(self.counter.read_text(), "2")

    def test_packaged_source_caches_metadata_and_detects_vcs_change(self):
        path = self.project / ".cargo_vcs_info.json"
        path.write_text(json.dumps({"git": {"sha1": "1" * 40}}))
        self.cargo("1" * 40)
        self.cargo("1" * 40)
        self.assertEqual(self.counter.read_text(), "1")
        path.write_text(json.dumps({"git": {"sha1": "2" * 40}}))
        self.cargo("2" * 40)
        self.assertEqual(self.counter.read_text(), "2")

    def test_worktree_tracks_its_actual_git_metadata(self):
        self.git("init", "-q")
        self.git("add", ".")
        self.git("commit", "-qm", "fixture")
        worktree = self.root / "worktree"
        self.git("worktree", "add", "--quiet", "--detach", str(worktree), "HEAD")
        self.project = worktree
        sha = self.git("rev-parse", "HEAD")
        self.cargo(sha)
        self.cargo(sha)
        self.assertEqual(self.counter.read_text(), "1")
        self.git("commit", "--allow-empty", "-qm", "next")
        self.cargo(self.git("rev-parse", "HEAD"))
        self.assertEqual(self.counter.read_text(), "2")

    def test_unknown_provenance_remains_conservatively_uncached(self):
        self.cargo("unknown")
        self.cargo("unknown")
        self.assertEqual(self.counter.read_text(), "2")
        (self.project / ".cargo_vcs_info.json").write_text("invalid metadata")
        self.cargo("unknown")
        self.cargo("unknown")
        self.assertEqual(self.counter.read_text(), "4")

    def test_dirty_tracked_non_rust_input_updates_the_suffix(self):
        (self.project / "README.md").write_text("original\n")
        self.git("init", "-q")
        self.git("add", ".")
        self.git("commit", "-qm", "fixture")
        sha = self.git("rev-parse", "HEAD")
        self.cargo(sha)
        (self.project / "README.md").write_text("modified\n")
        self.cargo(sha + "-dirty")
        self.git("checkout", "--", "README.md")
        self.cargo(sha)